DG7YBN / 144 MHz / GTV 2-9m
  Last Update Apr. 13th 2020




.......




Performance Data and Geometry
Pattern and VSWR
Download as File
X-pol Details
Stacking


GTV 2-9m Yagi   with bent Driven Element

EME + SSB narrow bandwidth version ... strictly G/T breeding

This medium length Yagi is balanced between gain and Antenna Temperature. However providing a modest bandwidth compared to its sister design, the GTV 2-9n. In comparison to most of the entries with exceptional G/T around 2.15 wl in the 144 MHz VE7BQH G/T table its T_ant is approximately 5 ... 10 K lower. Thus it may be very useful in difficult RXing scenarios like contests or EME from within a city with a small size 4-Yagi-Bay only. The bent DE (K6STI style) transforms from low impedance to 50 ohms at feed point for direct feed.
Date of issue of this design is 2018-03-25.

Current Profile




Performance Data

Gain vs. isotr. Rad.  14.0 dBi
Gain vs. Dipole       11.8 dBD
-3 dB E-plane         38.4 deg.
-3 dB H-plane         42.8 deg.
F/B                  -27.3 dB
F/R                  -26.7 dB
Impedance               50 ohms
VSWR Band Width     1.25:1 *
Mechan. Length        4492 mm
Electr. Length        2.15 λ

Stacking Dist. h-pol.
top-to-bottom         2.89 m
side-by-side          3.21 m

*) as in VE7BQH G/T table = at 145.00 MHz



Geometry



Table 1: GTV 2-9m, 8 mm elements on a 20 x 20 mm boom:



"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:


Boom shape: square
Boom: 25 x 25 mm
Offset rear: 40 mm
Offset front: 40 mm
 


Note: This includes a "Segmentation Density Correction" (SBC) of 2.05 mm



Table 2: GTV 2-9m, 8 mm elements on a 25 x 25 mm boom:



"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:


Boom shape: square
Boom: 25 x 25 mm
Offset rear: 40 mm
Offset front: 40 mm
 


Note: This includes a "Segmentation Density Correction" (SBC) of 2.05 mm



Sketch of Bent Dipole



This design has been viewed how often after the first built has been published in Mar. 2018?

Flag Counter







Pattern and VSWR Plots

Current distribution Elevation and Azimuth plot at 144.1 MHz

 


RL and SWR plot - simulated









Downloads

EZNEC file of this Yagi with 8 mm elem.  









X-pol Details


• Plane Offset is 90 mm.
• Stacking Distance is 3.01 m as average of h-pol. and v-pol. distances acc. DL6WU



Table 1: GTV 2-9m, 8 mm elements on a 25 x 25 mm boom:



"Ready to saw and drill" data for mounting elements on boom with BC according DG7YBN for standard insulators as sold by WiMo, Tino's Funkshop, HF Kits.nl, 7arrays:


Boom shape: square
Boom: 25 x 25 mm
Offset rear: 500 mm resp. 590 mm
Offset front: 130 resp. 40 mm
 


Note: This includes a "Segmentation Density Correction" (SBC) of 2.05 mm











Stacking



Stacking Dist.    DL6WU Formula
H-plane               2.851 m =  9.353 ft
E-plane               3.163 m = 10.377 ft

X-pol Stacking Dist.
3.01 m each plane


Elevation and azimuth plot and data of 4 Yagi bay using DL6WU stacking distances

 

AGTC_lite screenshot


Gain vs. isotr. Rad.  19.8 dBi
Gain vs. Dipole       17.6 dBD
-3 dB H-plane         17.2 deg.
-3 dB E-plane         19.2 deg.
F/B                  -30.6 dB
F/R                  -28.8 dB
T_los                  4.3 K
T_ant                228.5 K*
G/T                  -3.81 dB*
Theoretical numbers, no phasing line losses
nor imperfections caused by H-frame included
*) T_sky = 200 K, T_earth = 1000 K as in VE7BQH G/T table








73, Hartmut, DG7YBN



Flag Counter